DRM just proves "care taken"

I don't think it matters whether DRM is cracked or not, the BBC simply have to show that they took all reasonable precautions to protect the copyrights of the media they broadcast. If the DRM is cracked in those files then its the technology (i.e. Microsoft) that are liable, not the Beeb.

The BBC say that DRM is necessary to protect their rights, and open source software by definition does not support DRM, so what's the big problem here?